Effects Of Sophora Flavescens Ait On A Rat Model Of Chronic Pseudomonas Aeruginosa Pneumonia

Objective: To study the therapeutical effects of the Chinese medicinal herb, Sophora flavescensAit (SFA) on chronic Pseudomonas aeruginosa(PA) lung infection in a rat model . Methods:Rats were challenged intratracheally with alginate embedded PA strain PAO579 in theconcentration of 1x109 colony-forming units per milliliter(CFU/ML . SFA or sterile normalsaline (NS) was administered by gastric intubation once a day for two weeks starting on thesecond day after challenge. Two weeks post intratracheal challenge with P. aeruginosa,parameters were evaluated. Results :Two weeks after challenge, a remarkable serum antibodyresponse and significant infiltration of numerous polymorphonuclear leukocytes (PMN) in thelung tissues with higher IL-4,TNF-α and lower IFN-γ production in the lungs were found in theNS placebo treated group compared to the NS control group and SFA treated group.Significantly improved lung bacterial clearance (P<0.001) with milder macroscopic andmicroscopic lung pathology (P<0.01) were found in the SFA treated group compared to theplacebo treated group. Meanwhile, the incidence of lung abscesses in the SFA treated group wassignificantly lower than that in the placebo treated group (P<0.001) . Furthermore, the SFAtreatment lowered the serum level of anti-PA IgG, down-regulated the lung IL-4 and TNF-αlevels , but increased the production of IFN-γ in the lung. These findings indicate that SFA hasan effect of inducing Th1 type of immune response. The anti-PA activity test of SFA wasweakly positive whereas NS was negative. Conclusion: SFA treatment significantly enhancedlung bacterial clearance and reduced pathology, which might be associated with a shift of localimmune responding type from a Th2 like to Th1 like that might provide a better protection to therats with chronic Pseudomonas aeruginosa lung infection.